| 摘要 |
<p>The invention relates to novel thermoplastic, transparent copolyamide-based polyamide moulding compounds, containing diamines and dicarboxylic acids with aromatic nuclei, said compounds having a high refractive index > 1.60 with a low density, less than 1.3 g/cm3. Said materials also exhibit a low birefrigence, a high degree of hardness and scratch resistance. They are produced on conventional pressure autoclaves, according to a modified method. The inventive moulding compounds are shaped using thermoplastic processes and in relation to known substances such as PMMA or PC, they unite optically significant characteristics such as a high refractive index, degree of hardness and a high thermal stability in one product. In addition to the favourable combination of characteristics, moulded parts produced from the inventive moulding compounds exhibit the excellent chemical resistance inherent to polyamides. It is desirable for optical lenses to have an extremely low birefringence to prevent the formation of colour rings or distortion.</p> |
